(1) Every motor vehicle shall at all times be equipped with a muffler in good working order and in constant operation to prevent excessive or unusual noise, and no person shall use a muffler cut-out, bypass, or similar device upon a motor vehicle on a highway.

(2)(a) No motor vehicle first sold and registered as a new motor vehicle on or after January 1, 1971, shall discharge into the atmosphere at elevations of less than three thousand feet any air contaminant for a period of more than ten seconds which is:

(i) As dark as or darker than the shade designated as No. 1 on the Ringelmann chart, as published by the United States bureau of mines; or

(ii) Of such opacity as to obscure an observer's view to a degree equal to or greater than does smoke described in subsection (a)(i) above.

(b) No motor vehicle first sold and registered prior to January 1, 1971, shall discharge into the atmosphere at elevations of less than three thousand feet any air contaminant for a period of more than ten seconds which is:

(i) As dark as or darker than the shade designated as No. 2 on the Ringelmann chart, as published by the United States bureau of mines; or

(ii) Of such opacity as to obscure an observer's view to a degree equal to or greater than does smoke described in subsection (b)(i) above.

(c) For the purposes of this subsection the following definitions shall apply:

(i) "Opacity" means the degree to which an emission reduces the transmission of light and obscures the view of an object in the background;

(ii) "Ringelmann chart" means the Ringelmann smoke chart with instructions for use as published by the United States bureau of mines in May 1967 and as thereafter amended, information circular 7718.

(3) No person shall modify the exhaust system of a motor vehicle in a manner which will amplify or increase the noise emitted by the engine of such vehicle above that emitted by the muffler originally installed on the vehicle, and it shall be unlawful for any person to operate a motor vehicle not equipped as required by this subsection, or which has been amplified as prohibited by this subsection. A court may dismiss an infraction notice for a violation of this subsection if there is reasonable grounds to believe that the vehicle was not operated in violation of this subsection.This subsection (3) does not apply to vehicles twenty-five or more years old or to passenger vehicles being operated off the highways in an organized racing or competitive event conducted by a recognized sanctioning body.
[2006 c 306 § 4; 2001 c 293 § 1; 1977 ex.s. c 355 § 33; 1972 ex.s. c 135 § 1; 1967 c 232 § 3; 1961 c 12 § 46.37.390. Prior: 1955 c 269 § 39; prior: 1937 c 189 § 36; RRS § 6360-36; RCW 46.36.050; 1927 c 309 § 17; 1921 c 96 § 21; 1915 c 142 § 20; RRS § 6362-17.]

so in washington under 25 years old you cant modify the exhaust to be any louder then original, vehicle over 25 years old can be modified but must have a muffler. that is a simple law, I like how that reads, atleast it is in black and white

so maybe this is a dumb question because i'm not sure it's going to be too loud anyway.
if i run just one pipe it would be quiter than two pipes?
in my cj5 we just pointed the pipe towards the ground under the jeep to dampen noise, would that work in this case? my 5 didn't have headers on it.

With any decent muffler you should be OK unless you are running a full race cam setup. If you are going to be using it for a trail rig you need to have a baffled muffler, straight thru glasspack won''t pass muster with the feds for spark arresting ability. If they can pass a wire or thin rod through the muffler, they can write a ticket for it.